1. Field of the Invention
The present invention relates to a novel integrated process for production of oxygenated compounds (alcohols and ethers) for motor fuel use.
2. Background of the Prior Art
In order to reduce air pollution, public policy dictates reductions in pollutants arising from the operation of motor vehicles powered by petroleum derivatives, especially motor fuel gasoline. The first major act was the virtual elimination of tetraethyl lead as a motor gasoline octane improver, which has resulted in definite, and measurable, reductions in the amount of poisonous lead emitted into the atmosphere. At the same time, refiners were obliged to replace lost performance by increasing motor gasoline octane levels by other means. Refiners placed primary emphasis on increasing the severity of reforming and also added octane-enhancing chemicals, including more butanes; more aromatics (benzene, toluene and xylene); and alcohols (especially ethanol) and ethers (especially methyl tertiary butyl ether, or MTBE).
The outcome has been to successfully replace the lost anti-knock octane value from lead's disappearance, but concurrently, largely due to the increased reforming severity and higher levels of volatile butanes, the result has been to increase the evaporation of organic materials; to increase emissions of ozone-forming materials which cause urban smog; and to increase the aromatic content of motor gasoline, which leads to increased emissions of benzene, a known carcinogen. There is also the problem of increased emissions of poisonous carbon monoxide caused by the incomplete combustion of motor gasoline.
Legislation has been enacted in the U.S. (and other industrialized countries) which mandates certain fuel characteristics in order to control deleterious emissions. Such legislation characteristically stipulates reductions in fuel volatility; carbon monoxide emissions; ozone-forming chemicals; aromatic content; and toxic emissions. One of the primary means of achieving these reductions has been to specify minimum oxygen levels in all motor gasoline sold in certain locations and at certain times of the year (in some cases, year-round).
These mandated changes in the composition of motor gasoline will require significant increases in the amounts of oxygenated fuel materials being produced, especially:
methanol as a component of MTBE; PA1 methanol for use in an 85:15 methanol: gasoline blend (primarily in California); PA1 ethanol as a highly oxygenated material to be added to finished gasoline at the downstream end of the distribution chain; and PA1 ethanol as a component of ethyl tertiary-butyl ether (ETBE).
Large increases in the production of isobutylene to react with ethanol and methanol in producing ETBE and MTBE will also be required.